Gantry style CNC mill

[driftspin]

hello everyone, just a small update:

Giladv,


I am curious about your progress.

Any news?


Grtz Bert

Verstuurd vanaf mijn SM-A320FL met Tapatalk

[giladv]

hey driftspin,

unfortunately i'm kinda stuck as my friends CNC shop is busy with some real work haha (crying inside).
i have all of the "off the shelf parts" waiting in my home for the machined parts for almost a year now i think.

i promise to update as soon as things start moving again:)

Gilad

[Boyan Silyavski]

A question pops to my mind. Looking at the type of structure. WHY BT30 head?

I understand if you will tapp all day. But if not:

-you limit your speed more than half
-3kw spindle will cut through directly 1mm of mild steel with no problem and HSM with 6mm flute in that same mild steel any depth to 6mm!!! I know that from my machine
-forget about wood
-forget about engraving
- even aluminum needs 12k RPM at least with normal 6mm flute and 24k with 1/8 and similar

IMHO you limit severely your machine with this BT30 spindle. Its like driving a big black 4x4 near the seaside on a perfect road, while you must be driving a white cabrio sports car...


To me tapping could be solved differently and money spend towards better spindle, bigger spindle. At the end of the day it would be cheaper to make a dedicated servo+Z2+collet just for tapping.

Because from the looks that's not a machine for steel for me and i can not be easily convinced that it will be with that aluminum profiles.

Just some thoughts

PS. If you insist on this shape, size capability, then you need Epoxy Granite one, not a router, but mill. Ah, yeah. And extra spindle for small bits and engraving...

[JAZZCNC]

A question pops to my mind. Looking at the type of structure. WHY BT30 head?

IMHO you limit severely your machine with this BT30 spindle. Its like driving a big black 4x4 near the seaside on a perfect road, while you must be driving a white cabrio sports car...

Don't talk stupid. I'd rather have BT 30 spindle with option of ATC than 3Kw ER spindle anyday of the week. However what it really needs are high rpm rated bearings which can be replaced if needed.

Because from the looks that's not a machine for steel for me and i can not be easily convinced that it will be with that aluminum profiles.

Why do you doubt Profile.? Your machine is made from mild steel tube which very similiar in density to Aluminium profile but it's it's hollow so much more resonant which is bad news if trying to cut hard materials like steel.

Can tell you know I'd much rather have Gantry made from HD profile than from thin/medium wall Mild steel box section. Unless that box section was minimum of 10mm thick wall which then opens up all lot of other issues regards Mass etc.

Just because it's made from steel doesn't always make it better or stronger.

[Boyan Silyavski]

Don't talk stupid. I'd rather have BT 30 spindle with option of ATC than 3Kw ER spindle anyday of the week. However what it really needs are high rpm rated bearings which can be replaced if needed.

I'd rather not. I'd rather have a proper ATC spindle. A proper 7-15kw spindle. That BT30 spindle is limited to at most 10k RPM at the cost of rather expensive bearings.

If he needs a mill, a proper mill with BT spindle will be better, as DIY setup will not hold real tighter tolerance like a proper mill.

You know it, i know it. Thats why you have a router and a second hand proper mill. Ha, who are you trying to convince...

[JAZZCNC]

You know it, i know it. Thats why you have a router and a second hand proper mill. Ha, who are you trying to convince...

That wasn't the question thou was it and I'm not trying to convince anyone of anything except that your talking bollocks when say 3Kw ER collet based spindle with minimum usable speed of 5000rpm is better than Servo driven BT30 Spindle.!! . . . . Lets see your 3kw spindle do bit of rigged tapping or fly cut with 150mm head..

[giladv]

@Boyan Silyavski - valid question/points:)

my machine is intended to be the best, most versatile R&D tool i could build because of space limitations.
but also, it should be a fun project which i will learn the most from. so with that in mind:

- this setup has more tinkering and planning in it than just buying a single piece plug and play off the shelf part.
- this setup costs MUCH less to a comparable BT/ISO30 integrated high speed spindle. because of the actual spindle and because of the expensive balanced tool holders required for a high rpm spindle. we are talking more than X2 the cost for a complete setup.
- torque > speed for versatility. i can always cut slower with small tools but i you cannot use a facemill/tap/fly cutter/sketchy-chuck-setup-for-one time-lathe-work on a high speed spindle.
- reliability - this is very important. lets say the motor or the pneumatic cylinder is malfunctioning, what do you do? i can just swap them out separately with any other semi-compatible components.
- attachments - i can attach anything with a BT30 taper in it to the spindle (lasers/extruders/drag knives/lathe tools). but also i have an active axis on that attachment because of the servo on the other end.
- inertia/momentum - big heavy spindle attached to a big heavy servo and a tool holder are way more ideal for hogging/roughing operations.
- saying a 7k rpm spindle cannot do Al work or engraving is plain wrong. just looks at one of the many Tormac videos doing both and doing it great.

regarding the machine itself, it might not look like that in the CAD but all those profiles are the thickest and biggest i could find (120mm and 160mm). but also, because of their shape and internal structure they are at least as rigid as plain square steel tubes.

in terms of precision reliability, assuming those tubes were stress relieved in the first place, the second you weld them you will need to take them again for stress relief (or they will distort over time) + facing/grinding.
Item's Al profiles comes extremely straight and flat and you use fasteners so you can build with it inside an apartrment.

i intend to deal with vibration by filling the profiles with EG. the gantry profile will be filled with EG mixed with carbon fiber trimmings (for extra rigidity and slightly less weight in the cost of less damping capabilities)

i hope i answered your question:)
thanks!